全文获取类型
收费全文 | 2203篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 30篇 |
综合类 | 1篇 |
化学工业 | 287篇 |
金属工艺 | 101篇 |
机械仪表 | 112篇 |
建筑科学 | 6篇 |
矿业工程 | 59篇 |
能源动力 | 22篇 |
轻工业 | 26篇 |
水利工程 | 49篇 |
石油天然气 | 148篇 |
无线电 | 170篇 |
一般工业技术 | 635篇 |
冶金工业 | 293篇 |
原子能技术 | 186篇 |
自动化技术 | 87篇 |
出版年
2022年 | 24篇 |
2021年 | 29篇 |
2019年 | 27篇 |
2018年 | 58篇 |
2017年 | 58篇 |
2016年 | 63篇 |
2015年 | 28篇 |
2014年 | 50篇 |
2013年 | 77篇 |
2012年 | 66篇 |
2011年 | 57篇 |
2010年 | 60篇 |
2009年 | 55篇 |
2008年 | 67篇 |
2007年 | 73篇 |
2006年 | 58篇 |
2005年 | 51篇 |
2004年 | 76篇 |
2003年 | 39篇 |
2002年 | 36篇 |
2001年 | 45篇 |
2000年 | 44篇 |
1999年 | 30篇 |
1998年 | 59篇 |
1997年 | 54篇 |
1996年 | 40篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 41篇 |
1992年 | 29篇 |
1991年 | 27篇 |
1990年 | 22篇 |
1989年 | 30篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 25篇 |
1981年 | 23篇 |
1980年 | 25篇 |
1979年 | 29篇 |
1978年 | 27篇 |
1977年 | 41篇 |
1976年 | 48篇 |
1975年 | 34篇 |
1974年 | 35篇 |
1973年 | 30篇 |
1972年 | 25篇 |
1969年 | 25篇 |
排序方式: 共有2212条查询结果,搜索用时 20 毫秒
1.
A method of measuring and identifying the static parameters of a bipolar transistor is considered. The characteristic of the transistor, from which the parameters of the model are determined, is chosen depending on what group the calculated parameters belong to. The characteristics are measured in such a way that the equations of the model describing them can be reduced to the simplest form. 相似文献
2.
The properties of a spinel copper cobaltite obtained by thermal decomposition of mixed nitrates of both metals at 350°C and normal pressure are described. It has been shown that the maximum copper content (x) in the spinel CuxCo3?xO4 does not exceed 0.9. When the copper amount in the initial mixture is higher a second phase CuO is formed. The copper ions are distributed over the A- and the B-sites of the spinel lattice, i.e. the spinel is partially inverted. Such a model explains well the data obtained about the lattice parameter, IR-absorption and the magnetic susceptibility of the samples with different x. 相似文献
3.
4.
The article established the regularities of change of the physicomechanical characteristics and strength of glass textolites in single and repeated thermal loading. It shows that under multiple loading the intense loss of strength of the investigated materials is due to increased porosity on account of the large number of microcracks appearing in the structure. A correlation is obtained between the elastic and strength characteristics and porosity in dependence on the temperature of multiple heating which in the first approximation is described by a polynomial of second degree with respect to temperature, multiplied by the reciprocal of porosity.Translated from Problemy Prochnosti, No. 6, pp. 53–58, June, 1991. 相似文献
5.
N. Balchev D. Kovacheva V. Lovchinov K. Konstantinov K. Petrov 《Journal of Superconductivity》1993,6(1):49-54
The preparation conditions, phase composition, and superconducting properties of Bi-Pb-Sr-Ca-Cu oxide materials from different nominal compositions have been investigated. Nearly single-phase samples from Bi2Pb0.4Sr2Ca3Cu4O
y
, as well as from the proposed compositions Bi1.8Pb0.4Sr2Ca3Cu4O
y
and Bi1.8Pb0.4Sr2Ca2.5Cu3.5O
y
were obtained by a solid-state reaction in air. Samples with the third nominal composition showed the best superconducting properties (T
on=111 K and zero resistance atT
0=103 K). A possible mechanism for the 2223 phase formation in the three investigated compositions has been discussed. 相似文献
6.
A. P. Petrov 《Color research and application》1993,18(6):375-379
Color and Grassmann-Cayley Coordinates of Shape are considered in this article. The image irradiance equation for colored surfaces and the Grassman manifold λ of orbits Q = {B · h + c; detB ≠ 0} Where c is a vector sweeping the color space H, B is a 3 × 3 matrix, and h(x, y) is the color image of a Lambertian surface assumed to be a linear vector-function of the normal vectors. Different orbits Q(n) correspond to different shapes but they are invariant under color and illuminant transformation. Coordinates of an orbit Q in λ can be computed as 3 × 3 (2 × 2, sometimes) determining the elements of which are values of some linear functionals (receptive fields) of h(x, y). Based on the approach, a shape-from-shading algorithm was developed and successfully tested on the threeband color images of various real objects (an egg, cylinders and cones made of paper, etc.). © 1993 John Wiley & Sons, Inc. 相似文献
7.
O. N. Zavrazhnaya I. N. Oleinikov E. D. Naumov V. V. Petrov 《Chemical and Petroleum Engineering》1993,29(11):555-559
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 11, pp. 28–30, November, 1993. 相似文献
8.
V. P. Vasilevskii M. N. Mikhailov A. A. Petrov M. I. Rozhdestvenskii Yu. M. Cherkashov 《Atomic Energy》2006,100(4):295-301
The basic stages and directions of upgrading and reconstruction of the power-generating units of nuclear power plants with
RBMK reactors over a period of 20 yr since the Chernobyl accident are reflected in this paper. The greatest amount of work
was done in 1986–1990 on all units with RBMK-1000 and-1500 reactors which were operating at that time in the USSR. The purpose
of the upgrade was to improve the neutron-physical characteristics of the reactor cores, increase the response speed of the
safety and control system and decrease the positive effect of water outflow from the cooling loop of this system, increase
the flow capacity of the systems performing emergency discharge of the steam-gas mixture from the reactor, and improve the
basic operating documentation.
The subsequent stages of the upgrading and reconstruction concerned mainly the first-generation power-generating units (Nos.
1 and 2 units of the Leningrad and Kursk nuclear power plants). These works were performed to make the power-generating units
conform to the requirements of the modern normative documents on safety and allow for the possibility of these units to remain
in operation after the nominal 30-yr service life has been exhausted.
__________
Translated from Atomnaya énergiya, Vol. 100, No. 4, pp. 312–320, April, 2006. 相似文献
9.
L. Todorova T. Angelov Y. Marinov A. G. Petrov 《Journal of Materials Science: Materials in Electronics》2003,14(10-12):817-818
The linear electro-optic response of polymer-dispersed liquid crystal films has been studied. Micrometer-sized droplets of a cyanobiphenyl mixture (E7) were formed in a Norland Optical Adhesive 65 photopolymer by photopolymerization-induced phase separation. Samples with various average nematic droplet sizes were systematically investigated. The temperature dependence of the first-harmonic electro-optic spectra was obtained. Peculiar peaks and double peaks in the phase spectra were found at temperatures close to the clearing point. Samples with narrow distributions of droplet sizes were characterized by a double peak of the amplitude spectra in the low-frequency range. A flexoelectric origin of the first-harmonic spectra in confined nematic systems is discussed. 相似文献
10.
Translated from Izmeritel'naya Tekhnika, No. 10, pp. 38–39, October, 1992. 相似文献